Cách 1) Tìm hiểu phiên bản PHP mà tôi đang sử dụng và 2) Nâng cấp lên phiên bản mới nhất

Ive been trying to tackle this issue, but Im a hopeless non-developer. Is it possible for someone to detail how to do both of these tasks Ive mentioned in the title in great, tedious detail for me, in language that a four year old [wait; THREE year old] might be able to understand? Good golly, Id desperately appreciate the help. Thank you.